upgrades

type Context interface {
	// APIState returns an API connection to state.
	//
	// TODO(mjs) - for 2.0, this should return a base.APICaller
	// instead of api.Connection once the 1.x upgrade steps have been
	// removed. Upgrade steps should not be able close the API
	// connection.
	APIState() api.Connection

	// State returns a connection to state. This will be non-nil
	// only in the context of a controller.
	State() StateBackend

	// AgentConfig returns the agent config for the machine that is being
	// upgraded.
	AgentConfig() agent.ConfigSetter

	// StateContext returns a new Context suitable for State-based
	// upgrade steps.
	StateContext() Context

	// APIContext returns a new Context suitable for API-based upgrade
	// steps.
	APIContext() Context
}

type Model interface {
	Config() (*config.Config, error)
	CloudSpec() (environs.CloudSpec, error)
}

type Operation interface {
	// The Juju version for which this operation is applicable.
	// Upgrade operations designed for versions of Juju earlier
	// than we are upgrading from are not run since such steps would
	// already have been used to get to the version we are running now.
	TargetVersion() version.Number

	// Steps to perform during an upgrade.
	Steps() []Step
}

type OperationSource interface {
	// UpgradeOperations returns Operations to run during upgrade.
	UpgradeOperations() []Operation
}

type PreUpgradeStepsFunc func(_ *state.StatePool, _ agent.Config, isController, isMaster bool) error

type StateBackend interface {
	ControllerUUID() string
	StateServingInfo() (state.StateServingInfo, error)
	ControllerConfig() (controller.Config, error)
	LeaseNotifyTarget(io.Writer, raftleasestore.Logger) raftlease.NotifyTarget

	StripLocalUserDomain() error
	RenameAddModelPermission() error
	AddMigrationAttempt() error
	AddLocalCharmSequences() error
	UpdateLegacyLXDCloudCredentials(string, cloud.Credential) error
	UpgradeNoProxyDefaults() error
	AddNonDetachableStorageMachineId() error
	RemoveNilValueApplicationSettings() error
	AddControllerLogCollectionsSizeSettings() error
	AddStatusHistoryPruneSettings() error
	AddActionPruneSettings() error
	AddStorageInstanceConstraints() error
	SplitLogCollections() error
	AddUpdateStatusHookSettings() error
	CorrectRelationUnitCounts() error
	AddModelEnvironVersion() error
	AddModelType() error
	MigrateLeasesToGlobalTime() error
	MoveOldAuditLog() error
	AddRelationStatus() error
	DeleteCloudImageMetadata() error
	EnsureContainerImageStreamDefault() error
	RemoveContainerImageStreamFromNonModelSettings() error
	MoveMongoSpaceToHASpaceConfig() error
	CreateMissingApplicationConfig() error
	RemoveVotingMachineIds() error
	AddCloudModelCounts() error
	ReplicaSetMembers() ([]replicaset.Member, error)
	MigrateStorageMachineIdFields() error
	MigrateAddModelPermissions() error
	LegacyLeases(time.Time) (map[lease.Key]lease.Info, error)
	SetEnableDiskUUIDOnVsphere() error
}

type Step interface {
	// Description is a human readable description of what the upgrade step does.
	Description() string

	// Targets returns the target machine types for which the upgrade step is applicable.
	Targets() []Target

	// Run executes the upgrade business logic.
	Run(Context) error
}

type Target string